scholarly journals Mycelial Compatibility and Pathogenic Diversity Among Sclerotium rolfsii Isolates in the Southern United States

Plant Disease ◽  
2014 ◽  
Vol 98 (12) ◽  
pp. 1685-1694 ◽  
Author(s):  
Chenzhao Xie ◽  
Cheng-Hua Huang ◽  
Gary E. Vallad
Keyword(s):  
United States ◽  
South Carolina ◽  
Sclerotium Rolfsii ◽  
The Other ◽  
Southern United States ◽  
Southern Blight ◽  
Wide Range ◽  
Mycelial Compatibility ◽  
Pathogenic Diversity

Sclerotium rolfsii is a soilborne fungus that causes southern blight on a wide range of plants in tropical and subtropical regions of the world. Eighty-four isolates collected from Florida, Georgia, Louisiana, South Carolina, Texas, and Virginia were paired and assigned to 23 mycelial compatibility groups (MCGs), of which 11 MCGs consisted of a single isolate. Isolates within an MCG typically originated from different hosts and different geographical areas, with the exception of MCG 11. In all, 13 of the 15 isolates in MCG 11 originated from peanut in Georgia and Florida, while the other 2 isolates originated from potato in Virginia and from the ornamental Barlaeria cristata in Florida. Significant differences in the size and number of sclerotia produced in vitro existed between isolates from peanut and other hosts. Nineteen isolates representative of the most common MCGs (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 14, 15, 16, 17, and 18) were tested for pathogenicity on tomato, pepper, and peanut. All isolates were pathogenic on all hosts but virulence differed significantly among isolates. Isolates collected from peanut were the most virulent on all three hosts compared with isolates collected from tomato and pepper. ‘Georgia Green’ peanut was more susceptible to peanut isolates from Georgia than to the other tested isolates. Of the two tomato entries, the commercial tomato ‘Tygress’ was less susceptible than the previously reported resistant breeding line 5635M to many of the S. rolfsii isolates tested, with the exception of the peanut isolates collected from Georgia. These initial findings suggest that considerable variation exists among S. rolfsii isolates throughout the southern United States, with some indications of specialization for the isolates collected from peanut.

scholarly journals Sequence Variation in Two Protein-Coding Genes Correlates with Mycelial Compatibility Groupings in Sclerotium rolfsii

2013 ◽  
Vol 103 (5) ◽  
pp. 479-487 ◽  
Author(s):  
Efrén Remesal ◽  
Blanca B. Landa ◽  
María del Mar Jiménez-Gasco ◽  
Juan A. Navas-Cortés
Keyword(s):  
Rna Polymerase Ii ◽  
Sequence Variation ◽  
Geographic Origin ◽  
Sclerotium Rolfsii ◽  
Nuclear Ribosomal Dna ◽  
Causal Organism ◽  
Protein Coding ◽  
Protein Coding Genes ◽  
Wide Range ◽  
Mycelial Compatibility

Populations of Sclerotium rolfsii, the causal organism of Sclerotium root-rot on a wide range of hosts, can be placed into mycelial compatibility groups (MCGs). In this study, we evaluated three different molecular approaches to unequivocally identify each of 12 previously identified MCGs. These included restriction fragment length polymorphism (RFLP) patterns of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (rDNA) and sequence analysis of two protein-coding genes: translation elongation factor 1α (EF1α) and RNA polymerase II subunit two (RPB2). A collection of 238 single-sclerotial isolates representing 12 MCGs of S. rolfsii were obtained from diseased sugar beet plants from Chile, Italy, Portugal, and Spain. ITS-RFLP analysis using four restriction enzymes (AluI, HpaII, RsaI, and MboI) displayed a low degree of variability among MCGs. Only three different restriction profiles were identified among S. rolfsii isolates, with no correlation to MCG or to geographic origin. Based on nucleotide polymorphisms, the RPB2 gene was more variable among MCGs compared with the EF1α gene. Thus, 10 of 12 MCGs could be characterized utilizing the RPB2 region only, while the EF1α region resolved 7 MCGs. However, the analysis of combined partial sequences of EF1α and RPB2 genes allowed discrimination among each of the 12 MCGs. All isolates belonging to the same MCG showed identical nucleotide sequences that differed by at least in one nucleotide from a different MCG. The consistency of our results to identify the MCG of a given S. rolfsii isolate using the combined sequences of EF1α and RPB2 genes was confirmed using blind trials. Our study demonstrates that sequence variation in the protein-coding genes EF1α and RPB2 may be exploited as a diagnostic tool for MCG typing in S. rolfsii as well as to identify previously undescribed MCGs.

Black Bass Diversity: Multidisciplinary Science for Conservation

2015 ◽  
Keyword(s):  
United States ◽  
South Carolina ◽  
Native Species ◽  
Natural Habitat ◽  
Conservation Strategies ◽  
Southern United States ◽  
Physical Habitat ◽  
River Watershed ◽  
Black Bass ◽  
Redeye Bass

<em>Abstract</em>.—Rivers and streams of the southern United States contain more than 1,800 aquatic species, 500 of which are regionally endemic. At present, 34% of the fish species and 90% of the mussel species in peril nationwide are found in these systems. Declines in these imperiled species are due to many factors, including hydrologic alteration, degraded water quality, loss of instream and watershed connectivity, physical habitat degradation, and the negative effects of nonindigenous species (e.g., predation on, competition with, and hybridization with native forms). In addition, this situation is exacerbated through human population growth, competing water demands, land-use changes, and other interrelated issues. If unchecked, these issues will likely continue to contribute to the imperilment and loss of native species in the region. Of the nine described species and subspecies of black bass, six are endemic to the southern United States: Guadalupe Bass <em>Micropterus treculii</em>, Shoal Bass <em>M. cataractae</em>, Redeye Bass <em>M. coosae</em>, Florida Bass <em>M. floridanus</em>, Alabama Bass <em>M. henshalli</em>, and Suwannee Bass <em>M. notius</em>. In addition, undescribed species and subspecies also exist and all are in need of conservation measures to prevent them from becoming imperiled. In an effort to focus and coordinate actions to support the long-term persistence of endemic black bass populations, local, state, and federal agencies, universities, nongovernmental organizations, and corporations from across the region joined with the National Fish and Wildlife Foundation to form the Native Black Bass Initiative (NBBI). The NBBI provides regional conservation strategies, objectives, and targets to restore and preserve functional processes in those watersheds that support natural habitat conditions and sustainable populations of endemic black bass and other native fishes of the region. Initial actions implemented through the NBBI focus on addressing the conservation needs of Guadalupe Bass in streams of the Edwards Plateau ecoregion of Texas, Redeye Bass in the Savannah River watershed of Georgia and South Carolina, and Shoal Bass populations in the Apalachicola River watershed of Alabama, Florida, and Georgia.

scholarly journals Evaluation of the virulence of Sclerotium rolfsii isolates on Arachis hypogaea and screening for resistant genotypes in greenhouse conditions

2015 ◽  
Vol 8 (1) ◽  
pp. 1-11 ◽  
Author(s):  
A.A. Eslami ◽  
S.A. Khodaparast ◽  
S. Mousanejad ◽  
F. Padasht Dehkaei
Keyword(s):  
Plant Height ◽  
Block Design ◽  
Sclerotium Rolfsii ◽  
Soil Surface ◽  
Lesion Length ◽  
Randomized Block Design ◽  
Wide Range ◽  
Mycelial Compatibility ◽  
Pathogenicity Tests ◽  
Plant Maturity

Summary Sclerotium rolfsii is a soil borne pathogen responsible for root and stem rot on a wide range of crops. This study was conducted to identify the virulence of different S. rolfsii isolates on a susceptible local peanut germplasm and determine the resistance of 20 peanut genotypes to the most virulent isolate and also the relationship between virulence and mycelial compatibility groups (MCGs). Seventy eight isolates of this fungus from 10 host plants and six known MCGs were used in the experiment. The experiment was done in greenhouse conditions (25±5°C) using a complete randomized block design with three replications. Pots containing sterile soil (pH=6.7) were inoculated with barley seeds colonized by each isolate separately before being seeded with the peanut germplasm. Disease severity was assessed by scoring the wilting, yellowing or death of plants, mycelia or sclerotia production on the soil surface or on plant stem, stem area affected (%) and stem lesion length, at the stage of plant maturity. Also, shoot wet weight and plant height were recorded at this stage. According to the results of the pathogenicity tests, all of the isolates were virulent on the susceptible peanut germplasm and the virulence diff ered signifi cantly between the isolates (P≤0.01). There was no relationship between the virulence of the five groups of isolates identified in the present study and the MCGs. The peanut genotype 140, which was better than the others based on seed size, plant height and the canopy size, was also the most resistant one

scholarly journals Managing Fusarium Wilt of Watermelon with Delayed Transplanting and Cultivar Resistance

Plant Disease ◽  
2019 ◽  
Vol 103 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Anthony P. Keinath ◽  
Timothy W. Coolong ◽  
Justin D. Lanier ◽  
Pingsheng Ji
Keyword(s):  
United States ◽  
South Carolina ◽  
Soil Temperature ◽  
Fusarium Wilt ◽  
Disease Incidence ◽  
Southern United States ◽  
Cultivar Resistance ◽  
Race 1 ◽  
Triploid Watermelon ◽  
Marketable Fruit

Fusarium wilt of watermelon caused by Fusarium oxysporum f. sp. niveum is a serious, widespread disease of watermelon throughout the southern United States. To investigate whether soil temperature affects disease development, three cultivars of triploid watermelon were transplanted March 17 to 21, April 7 to 11, and April 26 to May 2 in 2015 and 2016 at Charleston, SC, and Tifton, GA into fields naturally infested with F. oxysporum f. sp. niveum. Incidence of Fusarium wilt was lower with late-season than with early and midseason transplanting in all four experiments (P ≤ 0.01). Cultivar Citation had more wilted plants than the cultivars Fascination and Melody in three of four experiments (P ≤ 0.05). In South Carolina, planting date did not affect weight and number of marketable fruit ≥4.5 kg apiece. In Georgia in 2016, weight and number of marketable fruit were greater with late transplanting than with early and midseason transplanting. In both states, yield and value for Fascination and Melody were higher than for Citation. Soil temperature averaged over the 4-week period after transplanting was negatively correlated with disease incidence for all four experiments (r = –0.737, P = 0.006). Transplanting after mid-April and choosing a cultivar with resistance to F. oxysporum f. sp. niveum race 1, like Fascination, or tolerance, like Melody, can help manage Fusarium wilt of watermelon and increase marketable yields in the southern United States.

scholarly journals ANTIGENIC MODULATION

1968 ◽  
Vol 127 (3) ◽  
pp. 523-539 ◽  
Author(s):  
Lloyd J. Old ◽  
Elisabeth Stockert ◽  
Edward A. Boyse ◽  
Jae Ho Kim
Keyword(s):  
Actinomycin D ◽  
Progressive Increase ◽  
The Other ◽  
Antigenic Modulation ◽  
Cytotoxic Test ◽  
Cell Divisions ◽  
Wide Range ◽  
D Region

Antigenic modulation (the loss of TL antigens from TL+ cells exposed to TL antibody in the absence of lytic complement) has been demonstrated in vitro. An ascites leukemia, phenotype TL.1,2,3, which modulates rapidly and completely when incubated with TL antiserum in vitro, was selected for further study of the phenomenon. Over a wide range of TL antibody concentrations modulation at 37°C was detectable within 10 min and was complete within approximately 1 hr. The cells were initially sensitized to C' by their contact with antibody, thereafter losing this sensitivity to C' lysis together with their sensitivity to TL antibody and C' in the cytotoxic test. The capacity of the cells to undergo modulation was abolished by actinomycin D and by iodoacetamide, and by reducing the temperature of incubation to 0°C. Thus modulation apparently is an active cellular process. Antigens TL. 1,2, and 3 are all modulated by anti-TL.1,3 serum and by anti-TL.3 serum. This modulation affects all three TL components together, even when antibody to one or two of them is lacking. aAnti-TL.2 serum does not induce modulation and in fact impairs modulation by the other TL antibodies. The influence of the TL phenotype of cells upon the demonstrable content of H-2 (D region) isoantigen, first shown in cells modulated in vivo, has been observed with cells modulated in vitro. Cells undergoing modulation show a progressive increase in H-2 (D region) antigen over a period of 4 hr, with no change in H-2 antigens of the K region. Restoration of the TL+ phenotype of modulated cells after removal of antibody is less rapid than TL+ → TL- modulation and may require several cell divisions.

scholarly journals Occurrence and Molecular Identification of Azoxystrobin-Resistant Colletotrichum cereale Isolates from Golf Course Putting Greens in the Southern United States

Plant Disease ◽  
2010 ◽  
Vol 94 (6) ◽  
pp. 751-757 ◽  
Author(s):  
Joseph R. Young ◽  
Maria Tomaso-Peterson ◽  
Lane P. Tredway ◽  
Karla de la Cerda
Keyword(s):  
United States ◽  
Creeping Bentgrass ◽  
Amino Acid Sequences ◽  
Golf Course ◽  
Southern United States ◽  
Common Disease ◽  
Putting Greens ◽  
Qoi Fungicides ◽  
Colletotrichum Cereale

Turfgrass anthracnose, caused by Colletotrichum cereale (≡C. graminicola), has become a common disease of creeping bentgrass and annual bluegrass putting greens throughout the southern United States. Strobilurin (QoI) fungicides such as azoxystrobin are single-site mode-of-action fungicides applied to control C. cereale. In vitro bioassays with azoxystrobin at 0.031 and 8 μg/ml incorporated into agar were performed to evaluate the sensitivity of 175 isolates collected from symptomatic turfgrasses in Alabama, Mississippi, North Carolina, Tennessee, and Virginia. Three sensitivity levels were identified among C. cereale isolates. Resistant, intermediately resistant, and sensitive isolates were characterized by percent relative growth based on the controls with means of 81, 23, and 4%, respectively, on media containing azoxystrobin at 8 μg/ml. The molecular mechanism of resistance was determined by comparing amino acid sequences of the cytochrome b protein. Compared with sensitive isolates, C. cereale isolates exhibiting QoI resistance had a G143A substitution, whereas isolates expressing intermediate resistance had a F129L substitution. C. cereale isolates displaying azoxystrobin resistance in vitro were not controlled by QoI fungicides in a field evaluation. The dominance of QoI-resistant C. cereale isolates identified in this study indicates a shift to resistant populations on highly managed golf course putting greens.

scholarly journals Southern Blight of Tall Fescue and Bluegrass Caused by Sclerotium rolfsii in Italy

Plant Disease ◽  
2006 ◽  
Vol 90 (2) ◽  
pp. 246-246
Author(s):  
G. Polizzi ◽  
A. Vitale ◽  
I. Castello
Keyword(s):  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Poa Pratensis ◽  
Sclerotium Rolfsii ◽  
Aerial Mycelium ◽  
Kentucky Bluegrass ◽  
Plant Diseases ◽  
Fluorescent Light ◽  
Southern Blight

Tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.) are the main turfgrass species cultivated in Sicily (southern Italy) for ready lawn (sod) to ornamental purposes. In July 2004 and May 2005, a widespread disease was noticed in two turf nurseries on the eastern side of Sicily on a ready lawn mixture of F. arundinacea cv. Safari (94%) + P. pratensis cv. Cabaret (6%). Numerous yellow, circular- and crescent-shaped patches as much as 30 to 40 cm in diameter were observed. The turf usually died around the perimeter of the patch, but the grass remained green in the center of the ring with a tuft of green grass in the center (frog eye). Affected turf was initially reddish brown and turned brown as it died. Small, round and off-white or tan seed-like structures were dispersed on mycelial strands at the outer edge of the ring in the mat at the base of grasses. The pathogen was identified as Sclerotium rolfsii Sacc. The fungus was isolated directly as aerial mycelium or sclerotia or following surface disinfection (2 min in 0.5% NaOCl) and plating diseased tissues on potato dextrose agar (PDA). Sclerotia were observed in vitro in 7-day-old cultures. Pathogenicity was tested by inoculating two com-mercial ready lawn strips (80 × 100 cm) of two healthy turfgrass species each with three isolates of the fungus. Thirty sclerotia were placed at the base of stems. Noninoculated ready lawn strips served as control. All plants were covered with plastic bags, exposed to diffused daylight for 5 days, and then maintained in a growth chamber at 25 to 28°C under fluorescent light. Disease symptoms and southern blight signs like the ones observed in the field occurred 2 weeks after inoculation. S. rolfsii was reisolated from affected tissues. Symptoms were not detected on any of the non-inoculated ready lawn strips. The disease was serious enough that chemical treatments were required for its control. Southern blight was previously detected on bermudagrass and other cool-season turfgrass genera (1).To our knowledge, this is the first report of southern blight on tall fescue and bluegrass in Italy. Reference: (1) R. W. Smiley. Common Names of Plant Diseases. Diseases of Turfgrasses. Online publication. The American Phytopathological Society, St. Paul, MN.

scholarly journals Efficacy of Fungicides against Soil Borne and Grapevine Pathogens under In vitro Conditions

2021 ◽  
Vol 12 (5) ◽  
pp. 523-531
Author(s):  
Anjali Singh ◽  
◽  
Ratna U. Thosar ◽  
Vijayshree Chavan ◽  
Sujoy Saha ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Xanthomonas Campestris ◽  
Sclerotium Rolfsii ◽  
Inhibition Zone ◽  
Macrophomina Phaseolina ◽  
Research Centre ◽  
Grape Vine ◽  
Rhizoctonia Bataticola ◽  
Wide Range

In vitro bio-efficacy of the novel copper (NC101 and NCP102) and phosphonate (PN103 and PMN104) based fungicides against various soil borne and grape vine pathogens was evaluated at ICAR-National Research Centre for Grapes, Pune, Maharashtra, India during February - April 2021. The fungicides were screened against five bacterial pathogens viz. Xanthomonas campestris pv. citri, X. campestris pv. campestris, X. campestris pv. punicae, X. campestris pv. viticola and X. oryzae pv. oryzae and 10 fungal pathogens viz. Rhizoctonia bataticola, Sclerotium rolfsii, Cladosporium sp, Alternaria alternata, Colletotrichum gloeosporioides, Penicillium notatum, Magnaporthe oryzae, Fusarium oxysporium, Macrophomina phaseolina (Soyabean isolate) and Macrophomina phaseolina (Jute isolate) at different concentrations. Results indicated that among all the tested fungicides viz. NC101, NCP102, PN103 and PMN104, phosphonate based fungicides (PN103 and PMN104) were highly effective against bacterial isolates with zone of inhibition ranging between 8.75 - 31.12 mm in which X. campestris pv. viticola was found to express least inhibition zone. In case of pathogenic fungal isolates, similar trend was observed, most of the isolates showed cent percent inhibition at higher concentration of PN103 and PMN104. However Sclerotium rolfsii showed least or no inhibition when tested at different concentrations of fungicides. The chemicals exhibited wide range of inhibition and it was found to increase steadily with increase in concentrations of the test fungicides.

scholarly journals Inhibitory effect of antagonistic bacteria against Sclerotium rolfsii, causal agent of southern blight of common bean

2020 ◽  
Vol 39 (1) ◽  
Author(s):  
Juan Carlos Martínez-Álvarez ◽  
Flavio Camacho-Angulo ◽  
Yolani de Jesús Bojórquez-Armenta ◽  
Bardo Sánchez-Soto ◽  
Jesús Damián Cordero-Ramírez ◽  
...  
Keyword(s):  
Pseudomonas Putida ◽  
Common Bean ◽  
Sclerotium Rolfsii ◽  
Inhibitory Effect ◽  
Causal Agent ◽  
Antagonistic Bacteria ◽  
In Planta ◽  
Southern Blight ◽  
Acinetobacter Pittii

El objetivo del presente estudio fue seleccionar cepas bacterianas de la rizósfera del cultivo de frijol y determinar su potencial para el control de <em>Sclerotium rolfsii</em> bajo condiciones <em>in vitro</em> e <em>in planta</em>. Se recolectaron muestras de suelo en los municipios de Ahome, Guasave y Angostura, Sinaloa, México, durante el ciclo agrícola 2018-2019. Los aislados se evaluaron bajo condiciones <em>in vitro</em> y se seleccionaron los mejores para la evaluación <em>in planta</em> e identificación molecular (tres aislados) con base a la región 16S del ADN ribosomal. Se evaluaron 65 aislados bacterianos <em>in vitro</em> contra <em>S. rolfsii</em> con un porcentaje de inhibición de 2.5 a 65%. <em>Acinetobacter pittii </em>(COHUI06)<em>,</em> <em>Pseudomonas putida</em> (SANMI02) y <em>Burkholderia</em> sp. (GLS06) inhibieron 55, 60 y 65% bajo condiciones <em>in vitro</em>; además resultaron no hemolíticas. Solo <em>Burkholderia</em> sp. ejerció mayor porcentaje de inhibición <em>in planta</em> para el control de <em>S. rolfsii,</em> con reducción de incidencia y severidad de la enfermedad en un 40 y 50% respectivamente, y promovió el peso seco de la planta. Para <em>A. pitti</em> o <em>P. putida</em> no fueron eficientes para el control del hongo <em>in planta</em>. Se sugiere hacer estudios con las bacterias en invernadero y campo.

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